Methods and devices to control radiated spurious emission in rf antenna switches

Abstract

Methods and devices to control radiated spurious emission (RSE) in an RF antenna switch are presented. The RF antenna switch includes a through stack that includes at least one regular N-type FET transistor and a plurality of intrinsic N-type FET transistors, and a shunt stack that includes a plurality of intrinsic N-type FET transistors. During an inactive mode of operation, the regular transistor turns OFF to present a high impedance. The RF antenna switch includes a termination stack having a plurality of regular P-type FET transistors that are activated during the inactive mode to present a termination impedance to the antenna. A bias signal generator that remains partially active during the inactive mode of operation to generate positive and negative control voltages having magnitudes that are sufficiently high to maintain ON/OFF control of the transistors of the stacks.

1 . A radio frequency (RF) antenna switch, comprising:
 a first switch element coupled between a common port of the RF antenna switch and a first throw of the RF antenna switch, the first switch element comprising:
 a through stack comprising a plurality of N-type FET transistors arranged in series connection, the through stack coupled between the common port and the first throw; and 
 a shunt stack comprising a plurality of N-type FET transistors arranged in series connection, the shunt stack coupled between the first throw and a reference ground, and 
   a bias signal generation circuit comprising at least one charge pump, the bias signal generator configured to generate positive and negative bias voltages based on a positive supply voltage,   wherein
 the RF antenna switch is configured to operate according to an active mode and an inactive mode, the inactive mode defining a low power consumption mode of the RF antenna switch, 
 control voltages applied to the first switch element during the active mode comprise positive and negative voltages having the respective magnitudes of the positive and negative bias voltages, 
 the control voltages applied to the first switch element during the inactive mode comprise positive and negative voltages having respective magnitudes that are greater than zero and smaller than the respective magnitudes of the positive and negative bias voltages, and 
 during the inactive mode, the at least one charge pump is inactive. 
   
     
     
         2 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the positive voltage of the control voltages applied to the first switch element during the inactive mode is the positive supply voltage, and   the negative voltage of the control voltages applied to the first switch element during the inactive mode is an inverted version of the positive supply voltage having a magnitude that is substantially equal to a magnitude of the positive supply voltage.   
     
     
         3 . The radio frequency (RF) antenna switch according to  claim 2 , further comprising:
 a positive bias signal switch that is configured to selectively output one of the positive bias voltage or the positive supply voltage; and   a negative bias signal switch that is configured to selectively output one of the negative bias voltage or the inverted version of the positive supply voltage.   
     
     
         4 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the control voltages applied to the first switch during the inactive mode are configured to control the through stack to an OFF state and the shunt stack to an ON state to isolate the common port from the first throw.   
     
     
         5 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the plurality of N-type FET transistors of the through stack comprises at least one intrinsic N-type FET transistor.   
     
     
         6 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the plurality of N-type transistors of the shunt stack comprises at least one intrinsic N-type transistor.   
     
     
         7 . The radio frequency (RF) antenna switch according to  claim 6 , wherein:
 the plurality of N-type transistors of the through stack or of the shunt stack comprises at least one regular N-type transistor.   
     
     
         8 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 each transistor of the plurality of N-type transistors of the through stack or of the shunt stack is an intrinsic N-type transistor.   
     
     
         9 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 each transistor of the plurality of N-type transistors of the through stack and of the shunt stack is an intrinsic N-type transistor.   
     
     
         10 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the plurality of N-type FET transistors of the through stack comprises at least one regular N-type FET transistor.   
     
     
         11 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the plurality of N-type transistors of the shunt stack comprises at least one regular N-type transistor.   
     
     
         12 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 each transistor of the plurality of N-type transistors of the through stack or of the shunt stack is a regular N-type transistor.   
     
     
         13 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 each transistor of the plurality of N-type transistors of the through stack and of the shunt stack is a regular N-type transistor.   
     
     
         14 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the respective magnitudes of the positive and negative bias voltages are greater than three.   
     
     
         15 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the respective magnitudes of the positive and negative voltages of the control voltages applied to the first switch element during the inactive mode are greater than one.   
     
     
         16 . The radio frequency (RF) antenna switch according to  claim 1 , wherein:
 the bias signal generation circuit further comprises a negative voltage generator configured to generate a negative supply voltage based on the positive supply voltage,   the at least one charge pump includes a negative charge pump for generation of the negative bias voltage based on the negative supply voltage, and   during the inactive mode, the negative voltage generator is active for provision of the negative voltage of the control voltages.   
     
     
         17 . The radio frequency (RF) antenna switch according to  claim 1 , further comprising a first negative voltage generator configured to generate a first negative supply voltage based on the positive supply voltage,
 wherein:   the bias signal generation circuit further comprises a second negative voltage generator configured to generate a second negative supply voltage based on the positive supply voltage,   the at least one charge pump includes a negative charge pump for generation of the negative bias voltage based on the second negative supply voltage, and   during the inactive mode, the first negative voltage generator is active for provision of the negative voltage of the control voltages, and the second negative voltage generator is inactive.   
     
     
         18 . The radio frequency (RF) antenna switch according to  claim 17 , wherein:
 during the active mode, the first negative voltage generator is inactive, and the second negative voltage generator is active.   
     
     
         19 . A radio frequency (RF) antenna switch, comprising:
 a first switch element coupled between a common port of the RF antenna switch and a first throw of the RF antenna switch, the first switch element comprising:
 a through stack comprising a plurality of intrinsic N-type FET transistors and at least one regular N-type FET transistor arranged in series connection, the through stack coupled between the common port and the first throw; and 
 a shunt stack comprising a plurality of intrinsic N-type FET transistors arranged in series connection, the shunt stack coupled between the first throw and a reference ground. 
   
     
     
         20 . The radio frequency (RF) antenna switch according to  claim 19 , wherein:
 the RF antenna switch is configured to operate according to an active mode and an inactive mode, the inactive mode defining a low power consumption mode,   control voltages applied to the first switch element during the active mode consist of positive and negative voltages having respective magnitudes that are greater than one, and   the control voltages applied to the first switch element during the inactive mode have a magnitude equal to zero.   
     
     
         21 .- 29 . (canceled) 
     
     
         30 . The radio frequency (RF) antenna switch according to  claim 20 , further comprising:
 a bias signal generation circuit comprising at least one charge pump configured to generate the positive and/or negative voltages during the active mode based on a supply voltage,   wherein   during the inactive mode, the at least one charge pump is inactive, thereby causing the respective magnitudes of the positive and/or negative voltages to settle to zero.   
     
     
         31 .- 38 . (canceled)